Flying at the very edge is difficult during combat as we can only rely on the P-51 temp gauges. Trying to keep eyes on a small BF-109 and at the same time glance down to check temps is a good way to loose a fight.
While it might be difficult to fully simulate, we should probably hear that something is not running ok. There might even be some smoke after a while. Performance degradation etc.
The problem, as I see it, is how the engine damage is represented in DCS. The unrealistic CLONK! sound with the propeller seizing. Instant death. Even Nick Grey stated in an interview that it is "rubbish".